What are these larvae?

Answers

I believe they are Crane Fly grubs known as leather jackets, they eat roots of plants and are not good news, we all have them in our gardens, when I find them I give them to my chickens and of course wild birds love them. Here is more info http://www.just-green.com/gallery/main.php?g2_view=core.DownloadItem&g2_itemId=50

Hi Norfolk, thanks for the link. Those grubs look a little more translucent, although mine were covered in mud which may have made them appear less so. Any that get eaten, get eaten but I don't have anything to feed them to and I don't want to kill them just for the sake of it. I'll hold of with the pesticides and hope they don't cause too much damage.